I love the shading and the style of drawing. It's very creative, and yet simple.
I think maybe you should work on coloring in the lines a bit more, and perhaps blending the rain a bit to make it more realistic?
The cave is alright, but maybe look at a few pictures for reference next time. Shadows tend to be very specific in these cases. Darker towards the back, lighter towards the front.
Otherwise, Love this piece. The emotions are clearly present. 'Specially the pups. Made me laugh. ^_^